Fluids based on fluorocarbon compounds are widely used in systems for the transfer of heat by compression of vapor, in particular air conditioning, heat pump, refrigeration or freezing devices. These devices have it in common that they are based on a thermodynamic cycle comprising the vaporization of the fluid at low pressure (in which the fluid absorbs heat); the compression of the vaporized fluid up to a high pressure; the condensation of the vaporized fluid to give a liquid at high pressure (in which the fluid discharges heat); and the reduction in pressure of the fluid in order to complete the cycle.
The choice of a heat-transfer fluid (which can be a pure compound or a mixture of compounds) is dictated, on the one hand, by the thermodynamic properties of the fluid and, on the other hand, by additional constraints. Thus, a particularly important criterion is that of the impact of the fluid under consideration on the environment. In particular, chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) exhibit the disadvantage of damaging the ozone layer. Thus, nonchlorinated compounds, such as hydrofluorocarbons, fluoroethers and fluoroolefins, are from now on generally preferred to them.
However, it is necessary to develop other heat-transfer fluids exhibiting a lower global warming potential (GWP) than that of the heat-transfer fluids currently used and exhibiting equivalent or improved performances.
The use of ammonia as heat-transfer fluid is known. However, a number of problems are associated with this compound: a very high compressor outlet temperature, in comparison with hydrofluorocarbons; an absence of oil return and the need to install an oil separator; an authorized total charge sometimes limited due to the toxicity of the product.
The document WO 2007/126414 describes a large number of mixtures of heat-transfer compounds and in particular mixtures “comprising” 1,3,3,3-tetrafluoropropene (HFO-1234ze) and ammonia. No example of a composition comprising these two compounds (whether with or without additional compounds) is provided, nor any relative concentration range for these compounds.
The document US 2006/0243945 describes a large number of mixtures of heat-transfer compounds and in particular mixtures comprising HFO-1234ze and mixtures comprising ammonia, but the combination of these two compounds is not disclosed.
The document WO 2008/009922 describes heat-transfer compositions, in particular based on 1,2,3,3,3-pentafluoropropene (HFO-1225ye) and on tetrafluoropropene (HFO-1234) generally (preferably 2,3,3,3-tetrafluoropropene or HFO-1234yf), which can comprise additional compounds chosen from a list comprising in particular ammonia.
The document WO 2008/027555 describes heat-transfer compositions, in particular based on HFO-1225ye or based on HFO-1234yf, which can comprise an additional compound which can in particular be ammonia.
However, there still exists a need to develop other heat-transfer fluids which exhibit a relatively low GWP and which are capable of replacing the ordinary heat-transfer fluids.
In particular, it is desirable to develop other heat-transfer fluids having a low GWP which are quasi-azeotropic, indeed even azeotropic, and/or which exhibit good energy performances, in comparison with ordinary heat-transfer fluids (such as R404A or R410A).